Application of Molecular Imprinted Magnetic Fe3O4@SiO2 Nanoparticles for Selective Immobilization of Cellulase.

Magnetic Fe3O4@SiO2 nanoparticles were prepared with molecular imprinting method using cellulase as the template. And the surface of the nanoparticles was chemically modified with arginine. The prepared nanoparticles were used as support for specific immobilization of cellulase. SDS-PAGE results indicated that the adsorption of cellulase onto the modified imprinted nanoparticles was selective. The immobilization yield and efficiency were obtained more than 70% after the optimization. Characterization of the immobilized cellulase revealed that the immobilization didn't change the optimal pH and temperature. The half-life of the immobilized cellulase was 2-fold higher than that of the free enzyme at 50 degrees C. After 7 cycles reusing, the immobilized enzyme still retained 77% of the original activity. These results suggest that the prepared imprinted nanoparticles have the potential industrial applications for the purification or immobilization of enzymes.

Magnetic α-Fe2O3/Fe3O4 Heterostructure Nanorods: Fabrication and Cytotoxicity to A549 Cells.

The magnetic α-Fe2O3/Fe3O4 heterostructure nanorods were fabricated by an alcohol-solution direct combustion method. The influence of the calcination temperature on the composition and properties of the nanorods was investigated. When the calcination temperature was not greater than 400 °C, the magnetic α-Fe2O3/Fe3O4 heterostructure nanorods were obtained, and the saturation magnetization (Ms) of the magnetic α-Fe2O3/Fe3O4 heterostructure nanorods decreased with the calcination temperature increasing from 250 °C to 400 °C; when the calcination temperature was equal or greater than 450 °C, α-Fe2O3 nanorods were obtained. In addition, the effects of nanorods' concentration, nanorods' constituent, incubation time and magnetic field on A549 cytotoxicity were investigated. The cytotoxicity of the heterostructure nanorods appeared time-dependent and concentration-dependent, and the magnetic field could enhance the cytotoxicity of nanorods to A549.

Using galactitol dehydrogenase coupled with water-forming NADH oxidase for efficient enzymatic synthesis of L-tagatose.

L-Tagatose, a promising building block in the production of many value-added chemicals, is generally produced by chemical routes with a low yield, which may not meet the increasing demands. Synthesis of l-tagatose by enzymatic oxidation of d-galactitol has not been applied on an industrial scale because of the high cofactor costs and the lack of efficient cofactor regeneration methods. In this work, an efficient and environmentally friendly enzymatic method containing a galactitol dehydrogenase for d-galactitol oxidation and a water-forming NADH oxidase for regeneration of NAD+ was first designed and used for l-tagatose production. Supplied with only 3 mM NAD+, subsequent reaction optimization facilitated the efficient transformation of 100 mM of d-galactitol into l-tagatose with a yield of 90.2 % after 12 h (obtained productivity: 7.61 mM.h-1). Compared with the current chemical and biocatalytic methods, the strategy developed avoids by-product formation and achieves the highest yield of l-tagatose with low costs. It is expected to become a cleaner and more promising route for industrial biosynthesis of l-tagatose.

One-pot, two-step enzymatic synthesis of amoxicillin by complexing with Zn2+.

A one-pot, two-step enzymatic synthesis of amoxicillin from penicillin G, using penicillin acylase, is presented. Immobilized penicillin acylase from Kluyvera citrophila was selected as the biocatalyst for its good pH stability and selectivity. Hydrolysis of penicillin G and synthesis of amoxicillin from the 6-aminopenicillanic acid formed and D-p-hydroxyphenylglycine methyl ester were catalyzed in situ by a single enzyme. Zinc ions can react with amoxicillin to form complexes, and the yield of 76.5% was obtained after optimization. In the combined one-pot synthesis process, zinc sulfate was added to remove produced amoxicillin as complex for shifting the equilibrium to the product in the second step. By controlling the conditions in two separated steps, the conversion of the first and second step was 93.8% and 76.2%, respectively. With one-pot continuous procedure, a 71.5% amoxicillin yield using penicillin G was obtained.

Enhanced production of 6-aminopenicillanic acid in aqueous methyl isobutyl ketone system with immobilized penicillin G acylase.

Enzymatic hydrolysis of penicillin G for production of 6-amino-penicillanic-acid (6-APA) was achieved by using penicillin G acylase as catalyst in an aqueous-methylisobutyl ketone (MIBK) system. The optimization was carried out and it was found that the best conversion was improved 10% more than the aqueous system, which was obtained at the conditions: initial pH 8.0, 5.0% (W/V) substrate (penicillin G), and temperature at 35 degrees C, and the ratio of aqueous and organic phase was 3:1. The stability of the biocatalyst was studied at the operational conditions. After 5 cycles of semi-batch reactions, the residual activity of penicillin G acylase was 69.2% of the initial activity. There was no apparent loss of the yield of product. This process has a potential application in the industrial scale production of 6-APA because it simplifies the process effectively.

Nano-Graphene Enclosed Multi Nitrogen: Dynamic Hierarchical Self-Assemble Property for Lithium Ion Storage.

Led to significant capacity improvement to 1800 mA/h after 100 cycles for nano-graphene-N4, which is the first report for a carbonaceous materials anode. In addition, the doping level, id est, number of nitrogen atoms, had a significant influence on the molecular self-assembled structures through hierarchical self-assembly. As the nitrogen concentration increased, the d-space between the nanosheets increased from 3.4 to 4.3. The capacity of the nano-graphene increased greatly from 500 mAh/g for nano-graphene without N-doping to 1800 mAh/g for nano-graphene with nanographene-N4, indicating that the capacity is related to the structures, and was defined and the relationship between performance and structure was determined.

Preparation, Surface Modification, and Characteristic of α-Fe2O3 Nanoparticles.

The α-Fe2O3 nanoparticles were prepared via the co-precipitation process, and they were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The effect of the water bath temperature on the average grain size of the α-Fe2O3 nanoparticles was investigated. The minimum grain size of the α-Fe2O3 nanoparticles was 19.6 nm when the water bath temperature was 40 °C. Furthermore, the α-Fe2O3 nanoparticles were successfully modified with silica (SiO2) and chitosan (CTS) using the idea of nanoarchitectonics. the experimental results showed that, the average diameter of the as-prepared α-Fe2O3/SiO2 nanocomposites was around 65 nm; while, the average hydrodynamic diameter of the α-Fe2O3/CTS nanocomposites increased gradually with the increase of chitosan in solution. When the mass ratio of chitosan and the α-Fe2O3 nanoparticles reached 40:1, the diameter distribution range of the α-Fe2O3/CTS nanocomposites was very wide of 100- 900 nm, so the mass ratio of chitosan and the α-Fe2O3 nanoparticles was selected from 10:1 to 20:1 to be applied.

Fabrication of Magnesium Ferrites for Enormous Adsorbance of Neutral Red and Their Electrochemical Properties.

Magnetic magnesium ferrite nanoparticles were fabricated via the ethanol-assisted solution combustion and gel calcination route. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometer, Brunauer-Emmett-Teller (BET) surface area measurement, vibrating sample magnetometer (VSM) and X-ray diffraction (XRD) were applied to characterize magnetic magnesium ferrite nanoparticles which were prepared under the condition of 20 mL absolute alcohol and calcined at 600 °C for two hours. The results showed that the nanoparticles were spinel structure with the saturation magnetization of 183 emu·g-1, the average grain size of 52 nm, the specific surface area of 33.2 m² · g-1. In addition, the electrochemical property and adsorption mechanism of neutral red (NR) onto the magnetic MgFe2O4 nanoparticles were investigated. The adsorption results were conformed to the pseudo-second-order adsorption kinetic and Temkin model, which implied that the multimolecular layer chemical adsorption had occurred. Moreover, the pH had little effect on the process of the adsorption, and the value of the magnetic magnesium ferrite nanoparticles for NR adsorption was up to 555 mg · g-1.

Optimization on Adsorption Process of Congo Red onto Magnetic Ni0.5Cu0.5Fe2O4/SiO2 Nanocomposites and Their Adsorption Mechanism.

Magnetic Ni0.5Cu0.5Fe2O4/SiO2 nanocomposites were prepared via a solution combustion process, and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), Energy dispersive X-ray Spectroscopy (EDX) and vibrating sample magnetometer (VSM). The magnetic Ni0.5Cu0.5Fe2O4/SiO2 nanocomposites were employed to remove Congo red (CR) from aqueous solution, and the adsorption process was optimized by response surface methodology (RSM). The optimum conditions were the silica content of 12.6 wt%, the calcination temperature of 501 °C and the pH value of 7.13. The adsorption kinetics and the adsorption isotherm of CR onto magnetic Ni0.5Cu0.5Fe2O4/SiO2 nanocomposites at room temperature were investigated, and the intraparticle diffusion kinetics model and Redlich-Peterson isotherm model fitted well the respective process.

Preparation of Magnetic Ni0.5Zn0.5Fe2O4/ZnO Nanocomposites and Their Photocatalytic Performances for Methylene Blue in Aqueous Solution.

Magnetic Ni0.5Zn0.5Fe2O4/ZnO-R (NZFO/ZnO-R) nanocomposites are prepared via the rapid combustion-coprecipitation process, and they are characterized by the Fourier Transform Infrared Spectroscopy (FTIR), the X-ray Diffraction (XRD), the Scanning Electron Microscopy (SEM), the Energy Dispersive X-ray Detector (EDX), the Specific Surface Area (BET), the UV-vis Diffuse Reflection Spectroscopy (DRS), and the Vibrating Sample Magnetometer (VSM). The photocatalytic activity of NZFO/ZnO-R nanocomposites is assessed in ultraviolet light (365 nm) by decoloration of methylene blue (MB). The results show that the magnetic NZFO/ZnO-0.2 nanocomposites consist of particles and rods. The size of particles is 18 nm. The width and length of rods are 66 nm and 198 nm, respectively. NZFO/ZnO-0.5 nanocomposites have better photocatalytic performance than that of NZFO, ZnO and NZFO/ZnO-R (R = 0.2, 0.3, 0.4, 0.6, or 0.7) from the results. Through careful investigation of influencing parameters (the amount of catalysts, pH and concentration of MB solution), the degradation efficiency of MB is closely connected with the transparency of solution and surface charge of catalysts. The enhanced photocatalytic activity of NZFO/ZnO-0.5 nanocomposites can be ascribed to the matching band positions between ZnO and NZFO, which results in a low recombination between the photogenerated electron-hole pairs. The possible mechanism is proposed for the improved ultraviolet photocatalytic activity of NZFO/ZnO-0.5 nanocomposites.

Chinese Medicine Amygdalin and ß-Glucosidase Combined with Antibody Enzymatic Prodrug System As A Feasible Antitumor Therapy.

Amarogentin is an efficacious Chinese herbal medicine and a component of the bitter apricot kernel. It is commonly used as an expectorant and supplementary anti-cancer drug. ß-Glucosidase is an enzyme that hydrolyzes the glycosidic bond between aryl and saccharide groups to release glucose. Upon their interaction, ß-glucosidase catalyzes amarogentin to produce considerable amounts of hydrocyanic acid, which inhibits cytochrome C oxidase, the terminal enzyme in the mitochondrial respiration chain, and suspends adenosine triphosphate synthesis, resulting in cell death. Hydrocyanic acid is a cell-cycle-stage-nonspecific agent that kills cancer cells. Thus, ß-glucosidase can be coupled with a tumor-specific monoclonal antibody. ß-Glucosidase can combine with cancer-cell-surface antigens and specifically convert amarogentin to an active drug that acts on cancer cells and the surrounding antibodies to achieve a killing effect. ß-Glucosidase is injected intravenously and recognizes cancer-cell-surface antigens with the help of an antibody. The prodrug amarogentin is infused after ß-glucosidase has reached the target position. Coupling of cell membrane peptides with ß-glucosidase allows the enzyme to penetrate capillary endothelial cells and clear extracellular deep solid tumors to kill the cells therein. The Chinese medicine amarogentin and ß-glucosidase will become an important treatment for various tumors when an appropriate monoclonal antibody is developed.